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Biomedical subjects

K Toyama

Publications and source records attributed to K Toyama.

At least 379 records · Page 21Linked to original sources
PubMed1988

Myelodysplastic syndrome with Philadelphia-like chromosome without bcr rearrangement.

The case of a 62-year-old Japanese male with a myelodysplastic syndrome and a Philadelphia (Ph)-like chromosome, which probably involved bands 11q23 and 22q11, is presented. Cytogenetic analysis of bone marrow cells revealed a Ph chromosome as well as -5, -7, +8, +11, -16, and an extra Ph. Some of the cells had a normal karyotype. Molecular analysis using breakpoint cluster region probes (5' bcr and 3' bcr) did not detect a rearrangement within the bcr DNA sequences, indicating that the breakpoint at 22q11 occurred outside the bcr. Furthermore, the bone marrow cells from this patient did not express an 8.5-kb c-abl mRNA. Thus, the Ph chromosome in this case differs from that of Ph-positive chronic myelogenous leukemia, and the present case suggests that we should retain the term of "Ph-like chromosome" in such cases.

Anemia, Refractory, with Excess of Blasts↗
PubMed1988

Synaptic action of layer I fibers on cells in cat striate cortex.

The synaptic action of layer I (LI) and white matter (WM) fibers in cat striate cells was studied intracellularly in slice preparations. LI stimulation produced excitation only in layer II-III and V cells, and inhibition broadly in layer II-VI cells. WM stimulation produced both excitation and inhibition in most cortical cells. Kynurenate, a glutamate antagonist, strongly depressed WM-evoked excitation, but it left LI-evoked excitation considerably unaffected.

Animals↗
PubMed1988

myb oncogene in human hematopoietic neoplasia with 6q- anomaly.

Molecular and cytogenetic analyses were performed on human T-cell leukemia cell lines (PEER and MOLT-4) with the 6q- anomaly. The PEER cells contained an interstitial deletion of the long arm of chromosome 6, that is, del(6)(q13q21), as well as other changes. The MOLT-4 cells showed a terminal deletion of the long arm of chromosome 6, that is, del(6)(q24). The 700-bp BamHI/XbaI-digested c-myb probe hybridized to a 4.3-kb fragment in EcoRI digested DNAs from these two cell lines, showing no deletion, rearrangement, or amplification. On the other hand, ML cells [ML-1, -2 and -3; human myeloid/T-cell biphenotypic leukemia cell lines with del(6)(q24)] showed an amplification of the c-myb gene and had a high level of the c-myb-related mRNA at 3.5 kb. Though no amplification of the c-myb at the DNA level was noted in the PEER or MOLT-4 cell lines, apparent high expression of the c-myb was detected in these human T-cell neoplastic lines. These results indicate that high c-myb expression is related to lineage of hematopoietic neoplasia rather than to the 6q- change.

Chromosome Banding↗
PubMed1988

Molecular and clinical investigations in Philadelphia chromosome-negative chronic myelogenous leukemia.

We performed molecular studies in five cases of Philadelphia (Ph) translocation-negative chronic myelogenous leukemia (CML). Among the five, one case showed a 7q - anomaly; the remaining four had normal karyotypes. The 5' or 3' breakpoint cluster region (bcr) DNA probes detected rearrangements in two of the five cases. The two cases with bcr rearrangement showed clinical and hematologic manifestations similar to those with Ph-positive CML; for example, basophilia in the peripheral blood and marked hepatosplenomegaly. On the other hand, the three Ph-negative CML cases without bcr rearrangement manifested somewhat different clinical manifestation; that is, they did not respond to busulfan therapy in the chronic phase. Our observations suggest a heterogeneity in Ph-negative CML with at least two subtypes: one with a rearranged bcr gene showing clinical and hematologic features akin to those of CML with a Ph translocation, and the other without such a rearrangement and with a somewhat different clinical feature. Furthermore, the present data point to the possibility of the existence of Ph-negative CML without bcr rearrangement.

Adolescent↗
PubMed1988

Intracortical connectivity revealed by spike-triggered averaging in slice preparations of cat visual cortex.

Intracortical connectivity was studied in slice preparations of cat's visual cortex by spike-triggered averaging. The experiments documented the unitary postsynaptic potentials underlying the inhibitory and excitatory connections from layer III-IV border cells to supragranular cells, as demonstrated previously by cross-correlation studies. In addition the analysis demonstrated the existence of two excitatory connections, between supragranular and layer V cells, that were not detectable in previous cross-correlation studies.

Animals↗
PubMed1988

Neuronal responsiveness in area 21a of the cat.

Photic responsiveness was studied in cells of area 21a which was identified as a region containing few cells projecting to area 17, and was bounded to two other visual areas (posteromedial lateral suprasylvian area and area 19) providing abundant efferent projection to area 17. Area 21a cells were characterized by strong orientation, but demonstrated poor direction and end-stop selectivity, in contrast to strong direction or end-stop selectivity of cells in another two visual areas.

Animals↗
PubMed1988

Testicular tumor as the first manifestation of B-lymphoid blastic crisis in a case of Ph-positive chronic myelogenous leukemia.

We report an 8-year-old boy with Ph-positive chronic myelogenous leukemia (CML) who showed a testicular tumor as the first manifestation of blastic crisis. Pathological examination of the excised testis revealed marked infiltration of immature cells, whereas bone marrow remained in the chronic phase. Immunohistochemical and molecular examinations disclosed the immature cells to have B-lymphocyte surface determinants and immunoglobulin JH rearrangement. DNA obtained from the testis and peripheral blood cells showed similarly rearranged bcr configurations, indicating that infiltrating cells in the testis originated from the CML clone. Bone marrow showed B-lymphoid blastic crisis 4 months after testicular involvement.

B-Lymphocytes↗
PubMed1988

Do leukemia patients with chromosome 16 inversion--inv(16)(p13q22)--have a rare fragile site at 16q22?

Chromosomes were examined in the peripheral blood cells from three cases of acute myelomonocytic leukemia (AMMoL) with inv(16)(p13q22) in order to induce the rare fragile site at 16q22 [fra(16)(q22)] with distamycin-A and berenil. No chromosomal gaps, breaks, or reaRrangements at 16q22 were noted in lymphocytes treated from these cases, indicating that AMMoL patients with inv(16)(p13q22) do not always have the rare fragile site FRA16B, FRA(16)(q22). A predisposition to neoplasia in carriers of this fragile site is questionable.

Chromosome Banding↗
PubMed1988

Translocation t(3;4)(q26;q21) in myelodysplastic syndrome with megakaryoblastic proliferation.

A 74-year-old Japanese male with a 4-year history of refractory anemia with excess of blasts is reported here. Chromosome study revealed the bone marrow cells of this patient to contain a t(3;4)(q26;q21). Ultrastructural analysis of platelet peroxidase and immunocytochemical study using monoclonal antibody for platelet antigen revealed a large number of blasts in the bone marrow to be megakaryoblasts. Thus, this case was thought to be one of a myelodysplastic syndrome with excess of blasts including megakaryoblastic proliferation showing chromosome changes at 3q26 and 4q21. The relationship of the anomaly on the long arm of a chromosome #3, especially at band 3q26, to abnormal megakaryoblastic proliferation is discussed.

Aged↗
PubMed1988

Ki-ras-2 in acute lymphoblastic leukemia cells with chromosome change at 12p12.

Cytogenetic and molecular investigations were performed on a pre-B-lymphoblastic acute leukemic cell line (NALM-6). The NALM-6 cells contained a del(5)(q32) and an ins(12)(p12;?), chromosomal material of unknown origin being inserted between subbands 12p12.1 and 12p12.2. Chromosomal in situ hybridization using a 3.0-kb c-Ki-ras-2 probe showed a significant accumulation of grains on the proximal portion of the inserted chromosomal material (12p12.1), as well as on the normal chromosome #12 with a peak at 12p11p12. The signal intensity obtained after hybridization of the c-Ki-ras-2 specific probe to the NALM-6 cells DNA is comparable with the intensity of the signal after hybridization of the same probe with the control cell line (MC/B) DNA. The findings indicate that the c-Ki-ras-2 gene is neither amplified nor transposed in the NALM-6 cells.

Chromosome Banding↗
PubMed1988

Analysis of DNA from cells fixed in Carnoy's solution for cytogenetic study.

DNA for Southern blot analysis was obtained from cells fixed in Carnoy's solution for cytogenetic investigation. DNA samples were extracted from fixed cells obtained from Philadelphia chromosome positive chronic myelogenous leukemia patients and shown to have aberrant fragments hybridized with a bcr probe; no apparent degradation was noted. This method should be useful for detection of molecular changes in cells fixed for chromosome analysis.

Acetates↗
PubMed1988

Morphologic changes of neutrophils in myelodysplastic syndrome treated with recombinant human granulocyte colony-stimulating factor.

Two cases of myelodysplastic syndrome (MDS) were treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF). In both cases, an increase of peripheral neutrophil counts was noted with a peak within 12 hr after the rhG-CSF administration. Neutrophils with ring shaped or hypersegmented nuclei were noted in the peripheral blood during the treatment, and they disappeared promptly after discontinuation of the therapy. The results indicate that the rhG-CSF might have mobilizing and differentiating effects on neutrophils derived from the MDS clone.

Adult↗
PubMed1988

Long-term potentiation of synaptic transmission in kitten visual cortex.

1. Potentiation of synaptic transmission in visual cortex (areas 17 and 18) of kittens was investigated by extracellular recording of field potentials (FPs) and cortical units in cortical slices and whole-animal preparations. Responses to test stimulation (0.05 Hz) of the white matter (WM), lateral geniculate nucleus (LGN), and optic chiasm (OC) were documented before and after conditioning stimulation (2 Hz for 1 h). 2. In slice preparations of area 17, the FPs were always depressed during conditioning stimulation and were usually potentiated immediately after conditioning stimulation. Long-term potentiation (LTP) of FPs developed rapidly during the initial 1-2 h and continued to increase slowly for several hours after conditioning. 3. LTP of FPs was age dependent: LTP occurred most frequently (43/53) at the ages of 21-34 days, less frequently (4/7 and 5/11) at 14-20 and 35-41 days, and never (0/5 and 0/5) at 7-13 and 42-49 days. LTP age relationship determined as a ratio of the amplitudes of FPs after conditioning to that before conditioning was greater at 21-34 days (mean potentiation, 2.4 +/- 0.6) than at 14-20 or 35-41 days (1.7 +/- 0.5). 4. LTP was also documented by the shortening in latencies of orthodromic responses of cortical units sampled from 10 pairs of conditioned and unconditioned control slices. Unit responses were classified into mono- and polysynaptic groups according to the central delay, defined as the time required for their activation after the arrival of afferent impulses. The monosynaptic central delays were 0.22 ms shorter in conditioned (0.60 +/- 0.17 ms, n = 56) than in control slices (0.82 +/- 0.22 ms, n = 57); similarly, polysynaptic central delays were 0.66 ms smaller (1.70 +/- 0.43 ms, n = 51; and 2.36 +/- 0.79 ms, n = 51). Both differences were statistically significant (P less than 0.001). 5. There were laminar differences in LTP of mono- and polysynaptic transmission. LTP of monosynaptic transmission occurred throughout layers II-V (central delays shortened about 0.2 ms), whereas LTP of polysynaptic transmission was greatest in layer II (1.17 ms), moderate in layer III (0.66 ms), and slight in layer IV (0.3 ms). The time course of shortening in orthodromic latency in five polysynaptic units agreed with the time course of LTP of FP. 6. Location of synapses involved in LTP of synaptic transmission was studied by current source-density (CSD) analysis in slice preparations of area 17 during test stimulation of WM. CSD analysis demonstrated two components of current sinks (early and late), probably representing mono- and polysynaptic transmission.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗